The present invention relates to test instruments employed for in situ testing of electrophysiology catheters employed for in vivo studying of the electrical activities of the heart. Typically, catheters of this type contain plural surface electrodes which are of sufficient conductivity that, when inserted into the heart through a vein, the electrical activities of the heart may be remotely monitored through electrical leads extending from the catheter electrodes through the vein and externally of the subject.
Catheters of this type are frequently inserted in a patient experiencing problems with heart function; and, the recordings of the heart electrical activity, as sensed by the catheter electrodes, have proven to be very helpful to medical practitioners in evaluating abnormalities and malfunction of the heart.
Referring to FIG. 1, a plural electrode catheter denoted by Reference numeral 1 is shown inserted through a vein. The catheter is pushed through the vein until the catheter resides in the patients heart denoted by Reference 3. The plural electrodes of the catheter 1 are connected to individual electrical leads denoted by Reference numerals 4, 5, 6, and 7 which may be connected to a device for monitoring the changes in electrical properties of the heart as sensed by the electrodes.
Referring to FIG. 2, a .typical known heart catheter or probe is illustrated as having generally cylindrical electrically non-conductive body denoted by Reference numeral 8 which has disposed therealong at spaced longitudinal stations a plurality of annular electrodes denoted by Reference 9, 10, 11, 12 with the electrode denoted by Reference 12 being disposed at the end of the catheter body 8.
Each of the electrodes 9, 10, 11, 12 has an electrical conductor attached thereto and embedded in the body 8 and extending outwardly from the end thereof remote from the electrode 12 which conductors are denoted respectively by Reference 13, 14, 15, 16 in FIG. 2. It will be understood that the portions of the conductors extending externally of the body 8 are covered with electrically insulating material; and, the remote ends of the conductors each have attached thereto an electrical connector such as a plug jack as denoted by respectively Reference numerals 17, 18, 19, 20. The plug jacks 17, 18, 19, 20 are adapted to be plugged into corresponding sockets provided in an electrical test instrument which is selectively operable by the user to check for continuity and resistance for each of the electrode circuits.
Heretofore, prudent medical practitioners have desired to test a catheter for its electrical integrity. Thus it has been necessary to provide the electrical testing apparatus for this purpose. Known techniques for testing cardiac catheters have utilized a conventional ohm meter for checking continuity individually of each electrode which has required switching of test circuits to evaluate each catheter electrode serially. This procedure has proven to be somewhat complicated and time consuming.
The situation is further complicated by the variety of catheters commercially available to medical practitioners and of the variations in electrode size, spacing and characteristics. Thus, it has long been desired to provide a simple reliable and easy to use way or means of quickly performing the electrical tests on a heart catheter necessary to demonstrate its proper functioning. It has further been desired to provide such a way or means of rapidly testing a cardiac catheter in a way which is not complex and prohibitively costly for manufacture of the test equipment.